A filter is a two-port network that is selective to the frequency of the input signal, with signals of certain basic frequencies (usually a certain frequency band range) passing easily and signals of other frequencies not.

The filter composed only of RC components is called passive filter, and the filter composed of RC components and active devices is called active filter.

According to the different amplitude-frequency characteristics, passive and active filters can be divided into low-pass filter (LPF), high-pass filter (HPF), band-pass filter (BPF) and band-stop filter (BEF) four kinds.

effect

(1) Separation of useful signal and noise, improve the anti-interference and signal drying of the signal;

(2) Filter out uninterested frequency components to improve analysis accuracy;

(3) Separate a single frequency component from a complex frequency component.